The aim is to study the structure-function relationships of the apolipoproteins. Lipoproteins play important roles in the transport of lipids through plasma and also in atherogenesis. In addition to performing lipid transport (i.e. detergent-like) functions, apolipoproteins also are responsible for modulating most of the interactions of lipoproteins with enzymes and cell receptors. Monoclonal antibodies will be produced against apolipoproteins AI, AII, B-100, B-48 and E. The numbers of distinct epitopes on each apoprotein will be enumerated using competition and cotitration assays. By means of apoprotein fragmentation, chemical modification and partial apoprotein synthesis, epitopes will be assigned to regions of apoproteins. Expression of epitopes on native hololipoproteins of normal and dyslipoproteinemic subjects and on recombinant lipoproteins will be assessed in binding assays using antibodies and Fab fragments. Epitope expression will be connected with function, e.g., epitopes of apoE will be linked to the apoB,E and apoE receptor binding domains of apoE; apoAI epitopes will be linked to the LCAT activator function of apoAI. It is hoped that these studies will contribute to knowledge of lipoprotein structure and function.